BC547b Transistor

Hello. I'm less than an amateur when it comes to electronics but I am persistent. Any help or direction would be the greatest x-mas present I've EVER had! I cannot find a simple explanation regarding the collector, base and emitter on the BC547C transistor. I know a certain type of MOSFET will act as an on/off switch when a small current is applied. BUT I was under the impression that the BC547C transistor can also do this. But this is not why I write this. I was under the impression that the BC547C transistor can multiply voltage. I tried everything with a 1.5 battery and nothing happened. Is there a diagram that would make this BC547C transistor multiply voltage? Or is there a video available for boneheads like me? I'm not sure what the emitter, base or collector does. Or what level voltage it is intended for. Perhaps my transistor is defective? Are there ways to test the BC547C transistor to ascertain if the BC547C transistor is functioning properly? I cannot find tutorials that explain the use of the BC547C transistor in its simplest form. Thank you for any help you might provide!

It's a simple switch. A small current in the Base will result in a larger current flowing from Collector to Emitter.

Here's one used to switch a relay,


Mike.
Edit, notice the current flows in the direction of the arrow in the emitter connection.

light360 said:

..... I was under the impression that the BC547C transistor can multiply voltage. I tried everything with a 1.5 battery and nothing happened. Is there a diagram that would make this BC547C transistor multiply voltage?....

Click to expand...

Transistors or FETs do not Multiply Voltages. What happens is that they can control Current Flow. What happens is that a small current through the Base controls Large Currents through the Collector. Or, a small voltage on the Gate controls a Large current through the Drain. This current flowing through a resistor generates Large Voltages. That is how the Gain / Amplify / "multiply" comes about.

light360 The simple explanations that are given about transistors and mosfets make sense when the user has some experience but can get confusing. Yes, a transistor can increase output voltage BUT, BUT, BUT, .... they cannot simply increase the voltage of a battery or other power source. That is, YOU CANNOT expect to connect a transistor to a 9V battery and get 10 or 15v out of the transistor.

What a transistor CAN do is increase the voltage of a SIGNAL. That is, input a 50mV sine wave and output can be much larger but you need power rails (the 9v battery for example) and some resistors to divide voltage and limit current with your transistor to create a proper amplifier circuit.

An extreme amplifier can be a switch, where power is off (no current flows through it) when input signal to BASE is low (or off) and then allows significant current to flow when input is HIGH (0.7v or more (depending on value of BASE resistor)). This switching character can be part of a larger circuit that includes an inductor, capacitor and diode to create a "BOOST voltage converter" that can get higher Voltage output that you input.

I hope that this starts to clarify your understanding of a transistor.

Someone reccomend me at this forum to use this and play with it:
You can scope your circuitry.

also check this:
it helps me when i wanted to visualize how bipolar transistor works.
or if you can spend lot few hours watch this:

Thank you Pommie, Ramussons, MacIntoshCZ and Gophert. I am a remedial math wizard. Algebra was never given to me. The schematic's base has a 5 sided polygon labeled "IN". What does it represent? Why is a resistor @ 560 ohms there? I often see a resistor attached to a transistor and I wonder why. The collector is attached to ground. What does ground represent? A clamp on a rod pounded into the ground? The emitter has 5 volt positive lead connected to an inductor? with a diode. The box is a controller? What is this thing? I quit electronics out of frustration because I could not get my Arduino with code and stepper motor with the Pololu circuit to function. I've always been fascinated with automated food dispensers and how the stepper motors operate. I need a practical video using a transistor, batteries and simple LED along with any other component. What I find unanswered is why do the dots in the video representing electrons flow backwards. It isn't that it's all complex it's just that I do not know the terms and the mechanics of electronics. For instance, anode and cathode take on different meanings in electronics so what I have to do is write it down so I don't forget. It's a little like a first day in Russian language class and nyet and dah is all I know. Thanks.

@ 05:56 in the video the narrator called the collector an emitter. It's little mistakes like that that can throw the novice off course.

light360 said:

@ 05:56 in the video the narrator called the collector an emitter. It's little mistakes like that that can throw the novice off course.

Click to expand...

Package TO92 with pins sorted EBC like.
Darlington variant for higher amplification when lower currents are used for driving. Video is correct.
You should read some books. Its hard to begin. If your mother language is ENGLISH, its actually easier to begin.

To posted image. VCC is 5V, IN represents driven signal. Let say 3V3. Base current is Uresistor/ResistorValue.
Uresistor is Uin - Ube (3,3 - 0,7)V roughly. Ibase = 2,6/560ohms -> 4,6mA.
Transistor is working as switch. It will be saturated. Its not working in linear region. Transistor amplification factor also know as HFE in datasheets is variable to input current. Lets say its 20. Then this transistor is capable of switching load that wil draw 4,6*20mA.
Diode paralel to relay is to surge voltage peaks. when inductor is turned off it will make change his own polarity.
Diode is used when you are working with low frequency switching. At higher frequency you need RDC. (resistor, diode, capacitor).

light360 said:

The schematic's base has a 5 sided polygon labeled "IN". What does it represent?

Click to expand...

That is the input to the circuit.

Most circuit diagrams don't show the whole circuit, just the part that is of interest. This circuit doesn't show the power supply, or what drives the input. Here the input is going to be a voltage above about 3 V relative to ground to turn the transistor on, and near 0 V to turn the transistor off.

light360 said:

Why is a resistor @ 560 ohms there? I often see a resistor attached to a transistor and I wonder why.

Click to expand...

The voltage between the base and emitter can't exceed about 0.7V. The resistor is there to limit the current. If the input is 3 V, with 0.7 V on the base, there will be 2.3 V across the resistor so a current of around 4 mA will flow.

light360 said:

The collector is attached to ground.

Click to expand...

It's not the collector. It's the emitter.

light360 said:

What does ground represent? A clamp on a rod pounded into the ground?

Click to expand...

It could be, but here it just represents the point against which other voltages are measured. If it were on a car, it would probably be the body of the car.

On an architect's drawing, there's often a point that is the reference against which heights are measure. The ground point is a bit like that for voltage.

light360 said:

The emitter has 5 volt positive lead connected to an inductor? with a diode. The box is a controller? What is this thing?

Click to expand...

The box is a relay. A relay is an electromagnet, which has considerable inductance, but its purpose is to operate a switch. That is usually called the coil. The outline of the box sort of indicates the connection between the coil between terminals 2 and 5 and the switch which is between terminals 1, 3 and 4. Terminals 1 and 4 are connected by the relay when the coil has no current. Terminals 1 and 3 are connected by the relay when the coil has current flowing.

The circuit doesn't show what is connected to those terminals of the relay. There would usually be something, as that is usually the purpose of a relay.

The relay coil has inductance. When the transistor turns off, the current flowing in the collector of the transistor can change to zero very quickly. The inductance of the relay coil can cause a momentary voltage spike which can be very large. The diode allows the current in the relay to change much more slowly, reducing the voltage spike.

https://en.wikipedia.org/wiki/Flyback_diode has more information about how a diode can be connected like that.

Would any of you be so kind as to post a schematic using the BC547C transistor that would demonstrate the use of the BC547C transistor ? And could you be so kind as to post the values of any resistor, battery, wire, capacitor etc used in your schematic? Just to demonstrate that I'm only occasionally a lazy good for nothing I'll post a photo of my invention I call "amateur horror #1". I tired of the "helping hands" available at the various electronics stores so I created one made from 3/4" zinc bars and all thread rods with alligator clips and wing nuts galore. The base of my creation is non-skidding and it is quit heavy and everything locks up nice and tight.

light360 said:

Would any of you be so kind as to post a schematic using the BC547C transistor

Click to expand...

I already did.

Mike.